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How to Understand Camera Sensor Size (And Why It Matters)

Last updated: November 12, 2023 - 8 min read
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Camera sensor size can help you predict image quality before a camera even comes out of the box.

A camera’s sensor is the part of the camera that actually captures the image. It plays a big role in what the resulting image looks like.

But what does camera sensor size mean? And why does it matter? This beginner’s guide will answer those questions and more, so continue reading.

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Camera Sensor Sizes Explained

The camera sensor is like a single exposure of film, except it can be used over and over again. Just like photography film comes in different sizes, digital cameras have different sensor sizes.

In a digital camera, the sensor is like a solar panel that gathers the light to create an image. A larger camera sensor will gather more light, creating a better image overall.

Camera sensor sizes are standardized. This makes it easy to compare the size of the sensor in one camera to the size of the sensor in another.

But there is some variation. Canon’s APS-C is smaller than other manufacturers, for example. But the variations are small enough not to make a noticeable difference in the final image.

Excluding the expensive medium format digital camera, the standard camera sensor sizes are:

A camera sensor size chart
A camera sensor size chart
  • Full frame: A full frame sensor is based on the size of 35mm film, measuring 36 x 24mm. Full frame sensors are found in professional-level DSLRs and mirrorless cameras. Some high-end compact cameras also have one.
  • APS-C: An APS-C sensor crops the full frame image by about 1.5x, measuring 22 x 15mm. This is the sensor size found in most entry-level to mid-level DSLRs. They’re also found in some mirrorless and high-end compact cameras.
  • Micro Four Thirds: The Micro Four Thirds sensor launched with the start of the mirrorless camera. It was to find a happy medium between camera size and image quality. The Micro Four Thirds sensor measures 17 x 13mm and has a 2x crop factor compared to a full frame sensor. Olympus mirrorless cameras use a Micro Four Thirds sensor. So do most Panasonic mirrorless cameras.
  • One-inch sensor: Designed for compact cameras, the one-inch camera sensor measures 13.2 x 8.8mm and has a 2.7x crop factor. Many high-end compact cameras use one-inch sensors. They pack more quality than an entry-level compact camera, but not as much as a DSLR or mirrorless camera.
  • Compact and smartphone sensor sizes: The sensors in typical compact cameras and smartphones have more variation. All of them are small compared to the size of a full frame sensor. A 1/2.3-inch sensor is one of the most popular sizes, as is a 1/1.7-inch sensor.

Any sensor smaller than a full frame sensor has what’s called a crop factor. Because the camera sensor is smaller, the image is cropped tighter.

Full frame sensors offer the most quality. But there are a few perks to picking up a camera with a smaller sensor.

So what are the pros and cons of choosing a large sensor over a small one?

 A DSLR on a trip set up in a photography studio

The Pros of a Large Camera Sensor Size

Larger Camera Sensors Have Better Image Quality

Camera sensor size is one of the biggest indicators of image quality. But it’s not the only one. Other influencing factors are the number of megapixels, the design of the camera sensor, and the camera’s processor.

Larger camera sensors capture images with more light, detail, and that beautiful background blur, to name a few. And it usually captures less noise in images.

Larger Camera Sensors Gather More Light

One of the reasons larger camera sensors create better images has to do with light. The larger the sensor’s surface area, the more light it can gather in a single shot.

Larger camera sensors are excellent for low-light photography. A larger camera sensor gathers more light than smaller sensors with the same shutter speed and aperture.

That’s why they tend to do better at any type of shot where the lighting is limited. For example, photographing a night landscape or photographing a theater production, concert, or dark dance floor.

Flat lay of a photographers desk featuring laptop, DSLR camera, coffee cup

Larger Camera Sensors Handle High Megapixel Counts Better

Camera sensor size and megapixel count go hand-in-hand. But a higher megapixel count is better on a larger camera sensor than on a smaller one.

A 50 MP full frame sensor will have larger pixels than a 50 MP APS-C sensor. The pixels have more room on that larger sensor.

That’s why it’s easier to find a 50 MP full frame sensor than it is to find a 50 MP APS-C sensor.

More megapixels create a higher-resolution image with more details. But trying to fit a lot of megapixels on a smaller sensor creates problems when it comes to low-light photography.

A small sensor with 25 megapixels will have more noise at high ISOs than a full frame sensor with 25 megapixels.

Sweet portrait of a young boy holding a DSLR camera

Larger Camera Sensors Create More Background Blur

Ever wonder why you can’t get that nice soft background blur from your smartphone? Larger camera sensors make that nice soft background easier to attain. This is more difficult with a smaller sensor.

That’s why smartphone companies are faking background blur using artificial intelligence in portrait mode. The sensors are just too small for the real thing. If you want a shallow depth of field, you want a full frame camera and a lens with a wide aperture.

A DSLR camera set up on a tripod to take a portrait of a female model

The Cons of a Large Camera Sensor Size

Smaller Camera Sensors Allow for Better Zooms

Full frame cameras may take the cake when it comes to image quality and background blur. But if you want to get up close, a smaller sensor has a few perks.

The camera sensor’s crop factor means smaller sensors make it easy to get up close to the subject. Zoom lenses are also smaller and cheaper when designed for smaller sensor cameras.

For example, the Micro Four Thirds sensor has a 2x crop factor. That means a 300mm lens acts like a 600mm lens.

That’s a big consideration for photographers that can’t move closer to the subject. This includes wildlife photographers and sports photographers.

Overhead view of a camera body and three lenses

Smaller Camera Sensors Mean Smaller Cameras

In general, a smaller sensor size means a smaller camera body. There are some exceptions, like the large Olympus OM-D E-M1X that has a Micro Four Thirds sensor. But most of the time, smaller sensor cameras weigh less and are more compact.

If you want a good travel camera, a smaller sensor camera may be easier to pack. The growth of mirrorless camera changes this some.

It’s now easier to find a compact camera with a full frame sensor than ever before. But most Micro Four Thirds and APS-C mirrorless cameras are still more compact.

And smaller sensor sizes mean you get a crop factor. So you can get more effective magnification from any given lens. For example, a 150mm lens on a Micro Four Thirds system is effectively a 300mm lens.

This effect is most pronounced with the big telephoto lenses. Wide-angle lenses won’t be affected as much.

A candid shot of a woman holding a DSLR camera indoors

Smaller Camera Sensors Are More Budget-Friendly

One of the biggest reasons to skip the full frame sensor is the cost. Most full frame cameras are professional-level gear. There are some entry-level full frame cameras. But most full frame camera will set you back a pretty penny.

Photographers on a budget can get most of the same perks by choosing a mid-sized sensor. Sure, an APS-C sensor isn’t quite as good as a full frame sensor. But it is way ahead of smartphones and compact cameras.

Some smaller sensor cameras are able to pack in more high-end features without getting too expensive.


Camera sensor size is the biggest indicator of image quality. It’s also important to note that it’s not the only quality indicator.

A backlit sensor is also better than a non-backlit sensor of the same size. The camera’s processor handling those images also play a role in image quality. Newer processors tend to produce less grain on the image than older processors.

So what sensor size is right for you?

If you want maximum background blur and the best low-light performance, choose a full frame camera. If you want great photos on a budget, try an APS-C camera. And if you want a travel-friendly interchangeable lens camera or need some serious zoom power, consider a Micro Four Thirds sensor.

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